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Supplementary Figure S1. Crebbp deficiency results in accelerated germinal center derived B-cell lymphoma development in mice. Supplementary Figure S2. Ep300 deficiency results in accelerated germinal center derived B-cell lymphoma development in mice. Supplementary Figure S3. Western blots showing the knockdown efficiency of shRNAs against human CREBBP in human DLBCL MD901 cells and H3K27ac reduction in MD901 cells transduced with shRNAs against human CREBBP, and stacked bar plot showing the genome-wide distribution of CREBBP ChIPseq peaks in OCI-Ly7 cells. Supplementary Figure S4. GSEA enrichment plots showing correlation of genes with >25% loss of H3K27ac at enhancers in VavP-Bcl2/shCrebbp tumours with ranked expression change between B220+ lymphoma cells from VavP-Bcl2/shCrebbp tumours (n=3) and VavP-Bcl2/GFP tumours (n=3). NES, normalized enrichment score. Supplementary Figure S5. Venn diagram showing the overlap of H3K4me2+H3K4me3-H3K27ac+ (active enhancer) peaks between human tonsilar IgD+ Naïve B cells (NBs) and CD77+ germinal center B cells (GCBs). Supplementary Figure S6. Pathway analysis of down-regulated genes in top 500 differentially expressed genes between murine VavP-Bcl2/shCrebbp tumours and VavP-Bcl2/GFP tumours (left panel), or between CREBBP knockdown and scramble control human DLBLC MD901 cells (right panel). Supplementary Figure S7. Pathway analysis of genes with > 25% reduction of H3K27ac reads at promoters in murine VavP-Bcl2/shCrebbp tumors. Supplementary Figure S8. UCSC read-density tracks of normalized BCL6 (purple) and SMRT (orange) ChIP-seq reads in human tonsilar GCBs, H3K27ac ChIP-seq reads in human tonsilar NBCs (red) and GCBs (blue), and H3K27ac ChIP-seq in control scramble (Scr, green) and CREBBP KD (shCREBBP, turquoise) MD901 cells at the human CIITA and CD74 loci. BCL6 and SMRT peaks determined by MACS2 are indicated by grey bars under the read density track. Supplementary Figure S9. Stacked bar plots showing the frequencies of CREBBP somatic mutations in two cohorts of FL and one cohort of DLBCL primary patient samples. Supplementary Figure S10. The proportions of the Up (up-regulated) and Down (down-regulated) genes in the top 100, 500, and 1000 most differentially expressed genes of the respective cohorts profiled in Figure 3. Supplementary Figure S11. Representative flow cytometry analysis for FAS and GL7 of whole spleens from NS-DAD wild type (wt) or mutant (mut) animals. Supplementary Figure S12. Western blots showing the knockdown efficiency of shRNAs against human HDAC3 in DLBCL cell lines OCI-Ly7 and MD901 120 hr after induction of shRNA expression. The amount of HDAC3 was quantified by using ImageJ, and the ratio of shRNA knockdown samples and the control shLuc sample was indicated below the blots. Supplementary Figure S13. BCL6 and HDAC3 ChIP-qPCR at enhancers of CD74 or HLA-DOA (primer sequences please check Supplementary Table S12) in OCI-Ly1 cells transfected with either non-target siRNA (siNT) or BCL6 siRNA (siBCL6). Supplementary Figure S14. Quantification of HLA-DR measured by flow cytometry in shCREBBP or scramble transduced lymphoma cells MD901 and OCI-Ly18 in a second biological replicate experiment.

A list of CREBBP mutations in cohorts 1 and 2.

All the enriched pathways in various analyses.

A list of CREBBP mutations in cohort 3.

All pathways used in pathway enrichment analysis.

Patient info for cohorts 1 and 2.

A list of primer sequences used in Figure 5.

The authors have requested that this preprint be removed from Research Square.

Some miRNAs, including the miR-302 cluster, are critical regulators of the stemness state of embryonic stem cells and cell fate patterning. In this study, we evaluated the activity of the miR-302 core promotor in mice and human pluripotent stem cells, somatic tissue derivatives, and generated transgenic mice expressing EGFP under a miR-302 promoter. The expression of EGFP under the control of the miR-302 promotor was examined in the cell lines and somatic tissues of transgenic mice, transgenic blastocysts, and embryonic stem cells derived from transgenic blastocysts. Our results showed that the miR-302 promoter is highly expressed in the mouse and human pluripotent cells, weakly expressed in the somatic tissue derivatives, is highly expressed in both blastocysts and the first passages of transgenic embryonic stem cells, and lowly expressed in the somatic tissues of transgenic mice. It can be concluded that different temporal and spatial gene expression patterns occur during the embryonic and adult stages of cells in mice.

The objective of this study was to investigate the effect of a pre-eclampsia mobile application on the knowledge of pregnant women.Following development of a pre-eclampsia mobile application, we conducted a controlled before and after study during a three-month period in 2018. The study population consisted of pregnant women attended to obstetrician clinics and offices in Kerman, Iran of whom, 110 sample participants were divided into two intervention and control groups. The participants completed a questionnaire of pre-eclampsia knowledge at baseline and 1-month follow up. Data were analyzed using inferential statistics including chi-square, independent sample t-test, paired t-test and linear regression.A total of 108 pregnant women with an average age of 28 years participated in this study. There was no significant difference between the scores of the two groups before the intervention (p=0.94). Their difference after the intervention was highly significant (p0.001). The difference between the knowledge of the participants before and after the intervention was significant in the both groups (p0.05). The results showed that the knowledge score of the participants after the intervention was significantly associated with their group and assessment score before the intervention (p0.001).The results showed that the use of a mobile-based educational application improves the knowledge of pregnant women about pre-eclampsia. Increasing women's knowledge about pre-eclampsia may enables them to identify its signs and symptoms, resulting in the early detection and management of this condition, and likely reduction of its adverse consequences.IRCT2017050633837N1.

Cancer cells adapt their metabolic activities to support growth and proliferation. However, increased activity of metabolic enzymes is not usually considered an initiating event in the malignant process. Here, we investigate the possible role of the enzyme serine hydroxymethyltransferase-2 (SHMT2) in lymphoma initiation. SHMT2 localizes to the most frequent region of copy number gains at chromosome 12q14.1 in lymphoma. Elevated expression of SHMT2 cooperates with BCL2 in lymphoma development; loss or inhibition of SHMT2 impairs lymphoma cell survival. SHMT2 catalyzes the conversion of serine to glycine and produces an activated one-carbon unit that can be used to support S-adenosyl methionine synthesis. SHMT2 induces changes in DNA and histone methylation patterns leading to promoter silencing of previously uncharacterized mutational genes, such as SASH1 and PTPRM. Together, our findings reveal that amplification of SHMT2 in cooperation with BCL2 is sufficient in the initiation of lymphomagenesis through epigenetic tumor suppressor silencing. Parsa et al. report a mechanism of lymphoma initiation involving cooperation of BCL2 and increased activity of the metabolic enzyme SHMT2, which imparts changes in DNA and histone methylation.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus disease 2019 (COVID-19) is chronic, inflammatory. Although the exact mechanisms of COVID-19 have not been yet discovered some drugs are found helpful for its treatment. These drugs which are divided into some lines therapies, have demonstrated to be helpful for COVID-19 patients based on immune basic and its antiviral properties of the disease. Previous studies have been indicated that deterioration of COVID-19 condition is associated with a weaker immune system. Most of these therapies impact on the immune system and immune cells. Beside many beneficial effects of these drugs, some adverse effects (AE) have been reported in many experiments and clinical trials among patients suffering from COVID-19. In this review, we conclude some AEs of vitamin-D, zinc, remdesivir, hydroxychloroquine or chloroquine, azithromycin, dexamethasone, amantadine, aspirin reported in different papers and we continue the rest of the drugs in second part of our review article.

Alzheimer's is a neurodegenerative disease with high morbidity and mortality in the elderly, so, detection of its biomarker for definite diagnosis of Alzheimer's in the early stage of disease is a challenge. Amyloid beta peptide (Aβ) chosen as an Alzheimer's biomarker. Here, we developed novel, semi-solid, three-dimensional hydrogel matrices for ratiometric fluorescence detection of Aβ. This assay's great performance stems from the employment of a hybrid conjugate composed of Rhodamine B (RB), Carbon dots (CDs), and an Aβ probe entrapped in Polyvinyl alcohol (PVA), and then detection of fluorescence resonance energy transfer (FRET) that occurs in the presence of AuNP/target-Aβ, as a result of hybridization. The RB-CDs' fluorescence (at 582 nm and 675 nm under 430 nm excitation) is quenched in the presence of AuNPs, while the ratio of fluorescence (I

Here, we developed a facile route to synthesize two CDs with the maximum emission locates at 326 nm and 443 nm under 230 nm excitation. The absolute photoluminescence quantum yield (QY) is as high as 29% and 52% for CD-1 and CD-2 with strong blue-green fluorescence, respectively. The functionalized CDs (CDs-NH2, CDs-COOH) conjugated with antibodies used for simultaneous detection of two tumor-markers using fluorescence resonance energy transfer (FRET) strategy, when MoS2 nanosheets functionalized with ssDNA related aptamers applied as quencher. The response of sensor enhanced gradually with increasing of targets at range 0.05–8 pg/mL with detection limit (DL) 5.0 fg/mL for CA125, while for CA15-3 concentration range was 1.0–35 pg/mL and DL was 0.5 pg/mL. This strategy revealed a stable analytical performance for the detection of OVCAR-3 and MCF-7 cells lines ranging from 1000 to 10,000 cells/mL with DL 2–3 cells in 10 μL of injected sample. When the CDs-Ab was used in selective imaging of MCF-7 and OVCAR-3 cancer cells, a strong PL emission was observed. After incubation times, both the cells size and shape clearly remained without any change. The results demonstrate that the CDs are a potentially excellent bioimaging component in pathological diagnosis, biomedicine research and management of cancer diseases.

Family with sequence similarity 83 member H (FAM83H) protein-coding geneplay an essential role in the structural organization, calcification of developing enamel, and keratin cytoskeleton disassembly by recruiting Casein kinase 1 alpha (CSNK1A1) to keratin filaments. In this study, we have applied CRISPR Cas9 nickase (D10A) to knockout (KO) the Fam83h gene in NMRI outbred mice. We generated homozygous Fam83h KO mice (Fam83h Ko/Ko) through a premature termination codon, which was validated by Sanger sequencing in F0 generation. Next, we also bred the FAM83H KO for two generations. Reverse-transcription polymerase chain reaction and Western blot analysis approved the Fam83h KO mice. The Fam83h KO mice had evidence of normal morphology at the cervical loops, secretory and maturation stages, and mandibular molars. In comparison with the normal wild-type mice (Fam83h W/W), the F2 homozygous KO (Fam83h Ko/Ko) had sparse, scruffy coats with small body size and decreased general activity. Also, they had the natural reproductive ability and natural lifespan. In addition, delay in opening the eyes and dry eyes among infant mice were seen. The F1 heterozygous mice looked comparable to the normal wild-type mice (Fam83h W/W), which showed autosomal recessive inheritance of these phenotypes. The KO of FAM83H had controversial effects on the development of teeth and the formation of enamel. The phenotype defect in dental development and the enamel formation were seen in three mice among four generations. It can be concluded that null FAM83H in outbred mice not only showed the reported phenotypes in null inbred mouse but also showed normal lifespan and reproductive ability; dental deficiency in three homozygous mice; and the symptoms that were similar to the symptoms of dry eye syndrome and curly coat dog syndrome in all four evaluated KO generations.

Background: The long-term complications of hemodialysis deteriorate patients’ quality of life and lead to physical and mental discomfort. Physiologically, sports activities can play an important role in reducing these side effects including muscle cramps. Objectives: The aim of this study was, to determine the impact of isotonic exercise on the frequency of muscle cramps. Methods: This clinical trial was carried out on 60 hemodialysis patients admitted to the dialysis units of Shahrekord and Borujen hospitals in 2014. The intervention included an isotonic exercise program that was implemented during 10 sessions of constant cycling (each lasting 10 minutes) immediately before dialysis. The outcome variable was the number of muscle cramps in patients during the hemodialysis session. The data were analyzed in SPSS-16 using descriptive statistics (frequency, percentage, mean, and standard deviation) and inferential tests (independent and paired t-tests). Results: The mean frequency of leg cramps before the intervention was not significantly different between the two groups (P = 0.10). However, it was significantly different between the groups after the intervention (P = 0.001). Moreover, the number of muscle cramps in the experimental group was significantly lower after the intervention than before implementing the program (P = 0.03). Conclusions: The isotonic exercise of constant cycling has a considerable effect on decreasing the number of muscle cramps in hemodialysis patients. Hence, it is suggested that dialysis units provide facilities for constant walking and cycling to accelerate patients’ treatment.

Background/aim Recurrent pregnancy loss (RPL) is defined as two or more pregnancy losses. T-regulatory cells play an important role in the feto-maternal interface. Cytotoxic-T-lymphocyte antigen-4 (CTLA-4) is a molecule that downregulates the activation and proliferation of T cells. The objective of the current study was to investigate the possible association of CTLA-4+49A/G gene polymorphism with RPL among patients from the Iranian Azeri Turkish ethnic group. Materials and methods The study group/patients consisted of 101 women with the experience of two or more pregnancy losses and the control group consisted of 101 women with at least two live births, without any previous history of pregnancy loss and autoimmune diseases from the same ethnic group. The CTLA-4+49A/G was detected by polymerase chain reaction-restriction fragment length polymorphisms assay. Results The distribution of CTLA-4+49A/G genotype was AA, 38.61%; AG, 51.48%; GG, 9.9% in patients and AA, 37.62%; AG, 47.52%; GG,14.85% in controls (P-value: 0.2). Furthermore, no association in G-allele was observed in the patient and control groups (P-value: 0.5). Conclusion The results of the present study suggest that CTLA-4 does not have any association with RPL in the Iranian Azeri Turkish ethnic group.

MicroRNAs are a group of short non-coding RNAs that undertake various roles in different cell signaling pathways and developmental stages. They regulate gene expression levels at the post-transcriptional stage, which results in cleavage of mRNAs or repression of their translation. Some miRNAs, including the miR-302 cluster, are critical regulators for the stemness state of embryonic stem cells and cell fate patterning. The miR-302 cluster is located in the intron of a non-coding gene that has no other reported function, other than hosting miR-302, and grant a complex expression regulation through upstream its regulatory sequences. To date, analysis of the miR-302 expression pattern in a transgenic mouse model has not been reported. In this study, we generated transgenic mice that expressed EGFP driven by miR-302 upstream regulatory sequences that harbored the core promoter of its host gene. We examined the activity of the miR-302 promotor in somatic tissues of transgenic mice, transgenic blastocysts, and embryonic stem cells derived from transgenic blastocysts. Our results showed that miR-302 highly expressed in both blastocysts and the first passages of transgenic embryonic stem cells, and has low expression in the somatic tissues of transgenic mice. It could be concluded that different temporal and spatial gene expression patterns occur during the embryonic and adult stages in mice.

The present study shows the morphology, anatomy and chemistry of Tornabea scutellifera occurring in north eastern Iran . Most thalli are corticolouse, even though its thalus also shows some degree of vegetation on rocky substrates.

Somatic mutations in CREBBP occur frequently in B-cell lymphoma. Here, we show that loss of CREBBP facilitates the development of germinal center (GC)–derived lymphomas in mice. In both human and murine lymphomas, CREBBP loss-of-function resulted in focal depletion of enhancer H3K27 acetylation and aberrant transcriptional silencing of genes that regulate B-cell signaling and immune responses, including class II MHC. Mechanistically, CREBBP-regulated enhancers are counter-regulated by the BCL6 transcriptional repressor in a complex with SMRT and HDAC3, which we found to bind extensively to MHC class II loci. HDAC3 loss-of-function rescued repression of these enhancers and corresponding genes, including MHC class II, and more profoundly suppressed CREBBP-mutant lymphomas in vitro and in vivo. Hence, CREBBP loss-of-function contributes to lymphomagenesis by enabling unopposed suppression of enhancers by BCL6/SMRT/HDAC3 complexes, suggesting HDAC3-targeted therapy as a precision approach for CREBBP-mutant lymphomas. Significance: Our findings establish the tumor suppressor function of CREBBP in GC lymphomas in which CREBBP mutations disable acetylation and result in unopposed deacetylation by BCL6/SMRT/HDAC3 complexes at enhancers of B-cell signaling and immune response genes. Hence, inhibition of HDAC3 can restore the enhancer histone acetylation and may serve as a targeted therapy for CREBBP-mutant lymphomas. Cancer Discov; 7(1); 38–53. ©2016 AACR. See related commentary by Höpken, p. 14. This article is highlighted in the In This Issue feature, p. 1

We previously demonstrated that Fibroblast Growth Factor 10 (FGF10) and its receptor FGFR2b play a key role in controlling the very early stages of mammary gland development during embryogenesis [Mailleux, A.A., Spencer-Dene, B., Dillon, C., Ndiaye, D., Savona-Baron, C., Itoh, N., Kato, S., Dickson, C., Thiery, J.P., and Bellusci, S. (2002). Role of FGF10/FGFR2b signaling during mammary gland development in the mouse embryo. Development 129, 53–60. Veltmaat, J. M., Relaix, F., Le, L.T., Kratochwil, K., Sala, F.G., van Veelen, W., Rice, R., Spencer-Dene, B., Mailleux, A.A., Rice, D.P., Thiery, J.P., and Bellusci, S. (2006). Gli3-mediated somitic Fgf10 expression gradients are required for the induction and patterning of mammary epithelium along the embryonic axes. Development 133, 2325–35.]. However, the role of FGFR2b signaling in postnatal mammary gland development is still elusive. We show that FGF10 is expressed at high level throughout the adipose tissue in the mammary gland of young virgin female mice whereas its main receptor FGFR2 is found mostly in the epithelium. Using a rtTA transactivator/tetracycline promoter approach allowing inducible and reversible attenuation of the FGFR2b signaling throughout the adult mouse, we are now reporting that FGFR2b signaling is also critical during postnatal mammary gland development. Ubiquitous attenuation of FGFR2b signaling in the postnatal mouse for 6 weeks starting immediately after birth is not lethal and leads to minor defects in the animal. Upon dissection of the mammary glands, a 40% reduction in size compared to the WT control is observed. Further examination shows a rudimentary mammary epithelial tree with completely absent terminal end buds (TEBs), compared to a well-branched structure observed in wild type. Transplantation of mammary gland explants into cleared fat pad of wild type mouse recipients indicates that the observed abnormal branching results from defective FGFR2b signaling in the epithelium. We also demonstrate that this rudimentary tree reforms TEBs and resumes branching upon removal of doxycycline suggesting that the regenerative capacities of the mammary epithelial progenitor cells were still functional despite long-term inactivation of the FGFR2b pathway. At the cellular level, upon FGFR2b attenuation, we show an increase in apoptosis associated with a decrease in the proliferation of the mammary luminal epithelium. We conclude that during puberty, there is a differential requirement for FGFR2b signaling in ductal vs. TEBs epithelium. FGFR2b signaling is crucial for the survival and proliferation of the mammary luminal epithelial cells, but does not affect the regenerative potential of the mammary epithelial progenitor cells.

The vertebrate limbs develop through coordinated series of inductive, growth and patterning events. Fibroblast Growth Factor receptor 2b (FGFR2b) signaling controls the induction of the Apical Ectodermal Ridge (AER) but its putative roles in limb outgrowth and patterning, as well as in AER morphology and cell behavior have remained unclear. We have investigated these roles through graded and reversible expression of soluble dominant-negative FGFR2b molecules at various times during mouse limb development, using a doxycycline/transactivator/tet(O)-responsive system. Transient attenuation (≤ 24 hours) of FGFR2b-ligands signaling at E8.5, prior to limb bud induction, leads mostly to the loss or truncation of proximal skeletal elements with less severe impact on distal elements. Attenuation from E9.5 onwards, however, has an irreversible effect on the stability of the AER, resulting in a progressive loss of distal limb skeletal elements. The primary consequences of FGFR2b-ligands attenuation is a transient loss of cell adhesion and down-regulation of P63, β1-integrin and E-cadherin, and a permanent loss of cellular β-catenin organization and WNT signaling within the AER. Combined, these effects lead to the progressive transformation of the AER cells from pluristratified to squamous epithelial-like cells within 24 hours of doxycycline administration. These findings show that FGFR2b-ligands signaling has critical stage-specific roles in maintaining the AER during limb development.

Somatic mutations in CREBBP occur frequently in germinal center derived lymphomas such as DLBCL and FL. However whether or how these mutations might contribute to lymphomagenesis is still largely unknown. Most CREBBP mutations are predicted to result in loss of function since they target the histone acetyltransferase (HAT) domain or give rise to premature stop codon prior to the HAT domain. Here, we show that Crebbp shRNA knockdown (KD) accelerated lymphomagenesis in VavP-Bcl2 transgenic mice, a model that recapitulates human GC-derived lymphomas. The median time to lymphoma onset in VavP-Bcl2/CrebbpKD mice was 114 days, significantly shorter than control VavP-Bcl2/GFP mice (193 days, p=0.04). Histopathology revealed that VavP-Bcl2/CrebbpKD lymphomas were more aggressive and widely disseminated than VavP-Bcl2/GFP lymphomas. CREBBP can regulate gene enhancer function through H3K27 acetylation. ChIP-seq in VavP-Bcl2/CrebbpKD lymphoma cells revealed significant reduction of H3K27ac peaks compared to control lymphoma cells (N = 1717, Kolmogorov-Smirnov test, p To better understand mechanism we performed an integrative analysis of CREBBP signatures against databases of B-cell transcription factor and epigenome profiles. This analysis yielded significant enrichment (BH-adjusted p The opposing effects of BCL6/SMRT/HDAC3 and CREBBP on MHC class II could have implications for immune surveillance. Accordingly CREBBP KD induced significant loss of cell surface HLA-DR molecules (p Disclosures Scott: Celgene: Consultancy; Roche: Honoraria; Janssen: Consultancy; BC Cancer Agency: Patents & Royalties: Inventor on a patent licensed to NanoString Technologies. Tam:Millennium Pharmaceuticals, Inc.: Consultancy. Melnick:Janssen: Research Funding.

Canonical WNT signaling plays multiple roles in lung organogenesis and repair by regulating early progenitor cell fates: investigation has been enhanced by canonical Wnt reporter mice, TOPGAL, BATGAL and Axin2(LacZ). Although widely used, it remains unclear whether these reporters convey the same information about canonical Wnt signaling. We therefore compared beta-galactosidase expression patterns in canonical Wnt signaling of these reporter mice in whole embryo versus isolated prenatal lungs. To determine if expression varied further during repair, we analyzed comparative pulmonary expression of beta-galactosidase after naphthalene injury. Our data show important differences between reporter mice. While TOPGAL and BATGAL lines demonstrate Wnt signaling well in early lung epithelium, BATGAL expression is markedly reduced in late embryonic and adult lungs. By contrast, Axin2(LacZ) expression is sustained in embryonic lung mesenchyme as well as epithelium. Three days into repair after naphthalene, BATGAL expression is induced in bronchial epithelium as well as TOPGAL expression (already strongly expressed without injury). Axin2(LacZ) expression is increased in bronchial epithelium of injured lungs. Interestingly, both TOPGAL and Axin2(LacZ) are up regulated in parabronchial smooth muscle cells during repair. Therefore the optimal choice of Wnt reporter line depends on whether up- or down-regulation of canonical Wnt signal reporting in either lung epithelium or mesenchyme is being compared.

Rodent incisors regenerate throughout the lifetime of the animal owing to the presence of epithelial and mesenchymal stem cells in the proximal region of the tooth. Enamel, the hardest component of the tooth, is continuously deposited by stem cell-derived ameloblasts exclusively on the labial, or outer, surface of the tooth. The epithelial stem cells that are the ameloblast progenitors reside in structures called cervical loops at the base of the incisors. Previous studies have suggested that FGF10, acting mainly through fibroblast growth factor receptor 2b (FGFR2b), is crucial for development of the epithelial stem cell population in mouse incisors. To explore the role of FGFR2b signaling during development and adult life, we used an rtTA transactivator/tetracycline promoter approach that allows inducible and reversible attenuation of FGFR2b signaling. Downregulation of FGFR2b signaling during embryonic stages led to abnormal development of the labial cervical loop and of the inner enamel epithelial layer. In addition, postnatal attenuation of signaling resulted in impaired incisor growth, characterized by failure of enamel formation and degradation of the incisors. At a cellular level, these changes were accompanied by decreased proliferation of the transit-amplifying cells that are progenitors of the ameloblasts. Upon release of the signaling blockade, the incisors resumed growth and reformed an enamel layer, demonstrating that survival of the stem cells was not compromised by transient postnatal attenuation of FGFR2b signaling. Taken together, our results demonstrate that FGFR2b signaling regulates both the establishment of the incisor stem cell niches in the embryo and the regenerative capacity of incisors in the adult.

The key role played by of Fgf10 during early lung development is clearly illustrated in Fgf10 knockout mice, which exhibit complete lung agenesis. However, Fgf10 is continuously expressed throughout lung development suggesting extended as well as additional roles for FGF10 at later stages of lung organogenesis. We previously reported that the enhancer trap Mlcv1v-nLacZ-24 transgenic mouse strain functions as a reporter for Fgf10 expression and displays decreased endogenous Fgf10 expression (Mailleux et al., 2005). In this paper, we have generated an allelic series to determine the impact of Fgf10 dosage on lung development. We report that 80% of the newborn Fgf10 hypomorphic mice die within 24 hours of respiratory failure. These mutant lungs display severe hypoplasia, dilation of the distal airways and large hemorrhagic areas. Epithelial differentiation and proliferation studies indicate a specific decrease in the percentile of TTF1 and SP-B expressing cells correlating with reduced epithelial cell proliferation and associated with a decrease in activation of the canonical Wnt signaling in the epithelium. Analysis of vascular development shows a reduction in PECAM expression at E14.5, which is associated with a simplification of the vascular tree at E18.5. We also show a decrease in α-SMA expression in the respiratory airway suggesting defective formation of the alveolar smooth muscle cells. At the molecular level, these defects are associated with a decrease in Vegfa and Pdgfa expression likely resulting from the decrease of the epithelium/mesenchymal ratio in the Fgf10 hypomorphic lungs. Thus, our results indicate that FGF10 plays a pivotal role in maintaining epithelial progenitor cell proliferation as well as coordinating alveolar smooth muscle cell formation and vascular development.